Regulating dynamo-electric machines.



PATENTED JUNE 2, 1903.

H. e; REIST. REGULATING DYNAMO ELECTRIC MACHINES.

APPLICATION FILED MAR. 24, 1902.

Invenfor: Henr GRcisC.

N0 MODEL.

wltnesses.

UNITED STATES Patented June 2, 1903.

PATENT OFFICE.

HENRY G. REIST, OF SCI-IENECTADY,

NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEWYORK.

S ECI AT N forming part of Letters Batent No. 729,795, dated June 2,1903.

Application filed March 24,1902. Serial No. 99,590. (No model.)

To aZ-L whom it may concern.-

Be it known that I, HENRY G. REIsr, acitizen of the United States,residing at Schenectady, in the county of Schenectady, State of NewYork, have invented certain new and useful Improvements in RegulatingDynamo- Electric Machines, of which the following is a specification.

My present invention relates to com pounding of alternatingcurrentdynamo electric machines in such a manner as to compensate for theeffects of changes in speed.

The invention is particularly useful in connection with that type ofalternator now well known to the art as a compensated alternator,wherein alternating current flowing in leads of the machine is conveyedeither directly or inductively through the armature of a synchronouslydriven exciter, the voltage of which is varied by the armature reactionof this current in such a way as to compensate for the effects ofvarying power factor of the system to which the alternator is connected.

An alternator of the type mentioned while possessing the features ofautomatic regulation, as specified, is sensitive to changes in speed,and to overcome the effect of these changes in speed is the purpose ofthe present invention, the novel features of which I have pointed out inthe appended claims and set forth in the following description, which isto be taken in connection with the accompanying somewhat diagrammaticdrawing, which shows an embodiment of the invention.

At 1 is represented the main alternator, which in this case consists ofan internal revolving field (indicated by the dotted lines at 2) and anexternal stationary member carrying the main windings, in this instanceof the three-phase type, the terminals of which are indicated at 3, 4,and 5. These terminals convey current either directly, as shown, or, ifdesired, through the interposition of transformers, to translatingdevices of any desired character. As typical of such translating devicesI have represented motors 6 7 and banks of lights 8 9 10 as connected tothe mains leading from the terminals of the machine; but it is of courseto be understood that any other current-consuming devices or means maybe employed, if desired;

The exciter 11 for the main alternator 1 is represented as having itsarmature 12 mounted directly on the shaft 13 of the alternator; but, ifdesired, it is evident that it might be geared thereto or otherwisedriven in synchronism with the rotating member of the main alternator.This exciter does not difier essentially in structure from ordinaryexciters and is provided, as indicated, with the usual commutator 14,connected in the usual manner with the winding of the armature 12 andwith a field-magnet structure 15, having a winding in shunt to thecommutator. A suitable field-rheostat may of course be employed inconnection with this winding; but details of this characterit isbelieved unnecessary to show in the drawing. The terminals of theexciter are connected through leads 16 17 with collector-rings 18,mounted on the shaft 13, which collector-rings convey theexciting-current for the revolving field member 2 of the mainalternator.

To render the exciter responsive to variations in load and power factorof the current in the mains 19, 20, and 21 of the distribution system, Iprovide each main with a series transformer, the primary of thetransformer in each instance being connected in series with the mainwith which it is associated. Thus at 22,23, and 24 are indicated theprimaries of the three series transformers associated, respectively,with the mains 19, 20, and 21. The secondaries, 25, 26, and 27 of thesetransformers are connected in threephase relation to eachother, theconnection in this case being the ordinary Y connection, and the threeterminals 28, 29, and 30 are connected through leads, as shown, withthree collector-rings 31, 32, and 33, mounted on the shaft 13 of themain alternator and connected by taps (indicated in dotted lines at 34)in three-phase relation to the winding of the armature 12.

The arrangement as thus far described is well known in the art, and themode of regulation of the same is well understood, so that no detaileddescription of the same seems necessary in the present case. Thisregulation, however, does not compensate for changes in speed of thealternator 1, to correct which deficiency I make use of the followingarrangement: Around the primary of each of the series transformers Ishunta circuit containing reactances of opposite signsuch, for example,as an inductance-coil and a condenser. Since the drop of potentialacross theterminals of the primary of each series transformer isnecessarily small, I connect the several circuits containing reactancesof different sign not directly in shunt across the terminalsmentioned,butindirectly through a step-up transformer, the use of whichenables me to obtain the same capacity effect of a condenser by the useof a much smaller condenser than would be necessary if this indirectconnection were omitted and the desired connections made directly. Thusat 35, 36, and 37 are represented the step-up transformers connected,respectively, about the primaries 22, 23, and 24: of the transformers inseries with the alternating-current mains 19, 20, and 21. In series withthe secondary of each of these step-up transformers area condenser, aninductance-coil, and a re sistance, as indicated, respectively, at 38,39, and 40 in the secondary of the step-up transformer35, for example.The remaining stepup transformers are similarly provided withcondensers, inductances, and resistances.

The condenser and inductance in each of the secondaries mentioned aretuned or proportioned relatively to each other so that theirelectromotive forces counterbalance each other when current of thenormal frequency flows in the mains of the distribution system. Theresistance in series with each combination of capacity and inductanceserves to limit and to adjust the amount of current flowing in thesecondary of each step-up transformer. To overcome a dissymmetry ofvoltages and currents which may occur in practice, I find it effectualto interconnect the high-tension sides of the step-up transformers in Y,as indicated at 41.

In explaining the operation of the mechanism above described it will benoted that when current flows in the mains of the distribution system itdivides, the major part passing through the primaries 22, 23, and 2d ofthe series transformers and the remaining; or branch currents throughthe circuits feeding the step-up transformers from which the resistance,inductance, and capacity combinations are fed. In case of a variation infrequency of the main current of the alternator, which corresponds ofcourse to an alteration in speed of the alternator, the reactive effectsof the inductance-coil and condenser of each combination changeaccordingly. Thus if the speed of the alternator rises, and consequentlythe frequency of current in the mains increases, the reactive efiect ofthe inductance-coils increases, while that of the condensers decreases.The branch circuits supplying the step up transformers therefore carry alagging current, the effect of which is to cause a phase advancement ofthe currents in the primaries of the series transformers, which phaseadvancement is communicated through the secondaries of thesetransformers to the winding of the armature of the exciter. The polarline of the armature reaction d ue to the alternating current thus fedinto the armature is shifted, so as to decrease the strength of field ofthe exciter, thereby compensating for the increase of voltage of theexciter which would otherwise exist due to increased speed of driving.In a similar manner a decrease in speed of the main alternator operatesto produce a preponderating effect of the condensers in the secondariesof the step-up transformers 35, 36, and 37, the primary circuits ofwhich therefore carry a leading current. The resultingaction istherefore equivalent to shunting a condenser about the primaries of eachof the series transformers, the effect of which is to cause aretardation or lag of current in these primaries, which retardation orlag is transmitted through the secondaries of these transformers to theexciterarmature 12 in the manner already set forth. In this case thepolar line of the armature reaction is shifted in a direction oppositefrom that first mentioned, and thereby operates to strengthen the fieldof the exciter, thus compensating for the decrease in voltage whichwould otherwise take place by reason of the drop in speed of rotation ofthe armature.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is-

1. The combination of an alternator,asynchronously-driven exciter, meansfor conveying to the armature of the exciter a part of the current ofsaid alternator,- and means re-' sponsive to variations in speed of saidalternator for causing a variation in phase of the current thus conveyedto the exciter relatively to the main current of the alternator.-

2. The combination of an alternator, a synchronously-driven exciter,series transform= ers in leads of said alternator, connections betweenthe secondaries of said transformers and the armature of said exciter,and shuntcircuits about the primaries of said series transformers, saidshunt-circuits each carry ing a leading current when the speed of saidalternator is below normal, and a lagging current when the speed of saidalternator is higher than normal.

3. The combination of a dynamo-electric machine, an exciter therefor,atuned circuit fed with current from said dynamo-electric machine, andmeans operatively related to said tuned circuit for regulating saidexciter in response to variation in speed of said dynamo-electricmachine.

4. The combination of an alternating-current dynamo-electric machine, atuned circuit supplied therefrom, and means operatively related to saidtuned circuit for regulating said dynamo-electric machine in responsetochanges of frequency of current supplied to said tuned circuit.

5. The combination of an alternating-current dynamo-electric machine, acircuit containing reactances of opposite sign, means for supplying saidcircuit with current from said dynamo-electric machine, and meansresponsive to the phase of-current in said circuit for regulating saiddynamo-electric machine.

6. The combination of an alternating-current dynamo-electric machine, anexciter therefor, a series transformer in a lead of said dynamo-electricmachine, a circuit containing resistance, self-induction and capacitysupplied with current from connections across the primary of saidtransformer, and

HENRY G. REIST.

Witnesses:

BENJAMIN B. HULL, HELEN ORFORD;

